Hello, can you tell me, if I want to create an application using a very large number of variables, how many of them can I create for one screen? Can I be used around 500 or 1000? Thank you so much in advance for your reply!
Use a list. (or a dictionary if you need to identify each number with a text/label)
You probably can use a 1000 or so variables or more on a single screen.
Why do you think you need that many variables Alex? 
Read the introductory articles: